to oneself. Evaluations underlie and generate desires, emotions, and goals. His judgments of what is for him or
against him determine the ends a man sets himself, as well as the means by which he seeks to achieve them.
If a man's values and goals are in conflict with the facts of reality and with his own needs as a living organism, then
he unwittingly moves toward self-destruction. Thus, man's survival requires that the evaluative function of
consciousness be ruled by the cognitive function—i.e., that his values and goals be chosen in the full context of his
rational knowledge and understanding.
Man is not infallible, and mental health does not require never making an error of knowledge or judgment. The
concept of mental health pertains to the method by which a mind functions. It pertains to the principles by which a
mind operates in dealing with the material of reality. It pertains to a man's "psycho-epistemology."^1
The concept of "psycho-epistemology" is crucially important, not only to the problem of mental health, but to the
entire subject-matter of this book. Let us, therefore, consider the meaning of this concept.
Psycho-Epistemology
As a field of scientific study, psycho-epistemology should be classified as a branch of psychology. It may be
described as the psychology of thinking (or of cognition).
Epistemology, of course, is a branch of philosophy; it is the science that studies the nature and means of human
knowledge. Its primary purpose is to establish the criteria of knowledge, to define principles of evidence and proof,
to enable man to distinguish between that which he may and may not regard as knowledge. Epistemology assumes,
or takes as its "given," a normal (i.e., healthy) consciousness; it assumes an intact mind intent on knowing the facts
of reality. Insofar as it is concerned with the internal operations of mind, it is concerned from one standpoint
exclusively: the standpoint of relevance to establishing the criteria of knowledge. Its basic concern is with the
relationship of ideas to reality—not with mental processes as such.
The study of mental processes as such is the province of psychology—most particularly, of psycho-epistemology.